The field of the invention relates generally to refurbishing gas turbine airfoil components. More specifically, the present invention is directed to systems and methods for polishing the surfaces of gas turbine airfoil components using abrasive media.
In a gas turbine, air pressurized in a compressor section is mixed with fuel and ignited to generate hot pressurized gases. The hot pressurized gases pass through a turbine section that converts the thermal and kinetic energy from the hot pressurized gases to mechanical torque acting on a rotating shaft or other element, thereby producing power used for both compressing the incoming air and driving an external load, such as an electric generator. As used herein, the term “gas turbine” may encompass stationary or mobile turbomachines, and may have any suitable arrangement that causes rotation of one or more shafts.
The air entering the gas turbine often contains gaseous, liquid and particulate matter that pass through the compressor section and degrade the surface finish of the rotating and stationary compressor airfoils. These and other contaminants may then be entrained in the hot pressurized gases that pass through the turbine section, which, along with the effects of heat and oxidation, similarly degrade the surface finish of the rotating and stationary turbine airfoils.
The effect of this degradation over time, particularly in the compressor section, is reduced gas turbine output and efficiency due to reduced aerodynamic performance of the airfoils. Current practice of refurbishing the airfoils typically includes manual polishing of the airfoil surfaces during planned maintenance periods, such as when the turbine rotor is removed during a major inspection. However, the manual polishing is time consuming and does not restore the surface finish to an as new condition.
In view of the above, there is a desire for improved systems and methods for restoring the surface finish of gas turbine airfoils during maintenance periods.